Catalyst system and its use in a polymerization process

ABSTRACT

The present invention relates to a catalyst system of a Group 15 containing metal catalyst compound and a Lewis acid aluminum containing activator and to a supported catalyst system thereof and to a process for polymerizing olefin(s) utilizing them.

FIELD OF THE INVENTION

The present invention relates to a catalyst system of a Group 15 containing transition metal catalyst compound and a Lewis acid aluminum containing activator and its use in the polymerization of olefin(s).

BACKGROUND OF THE INVENTION

Advances in polymerization and catalysis have resulted in the capability to produce many new polymers having improved physical and chemical properties useful in a wide variety of superior products and applications. With the development of new catalysts the choice of polymerization-type (solution, slurry, high pressure or gas phase) for producing a particular polymer has been greatly expanded. Also, advances in polymerization technology have provided more efficient, highly productive and economically enhanced processes. Especially illustrative of these advances is the development of technology utilizing bulky ligand metallocene-type catalyst systems.

More recently, developments have lead to the discovery of anionic, multidentate heteroatom ligands as discussed by the following articles: (1) Kempe et al., “Aminopyridinato Ligands—New Directions and Limitations”, 80^(th) Canadian Society for Chemistry Meeting, Windsor, Ontario, Canada, Jun. 1-4, 1997; (2) Kempe et al., Inorg. Chem. 1996 vol 35 6742; (3) Jordan et al. of polyolefin catalysts based on hydroxyquinolines (Bei, X.; Swenson, D. C.; Jordan, R. F., Organometallics 1997, 16, 3282); (4) Horton, et.al., “Cationic Alkylzirconium Complexes Based on a Tridentate Diamide Ligand: New Alkene Polymerization Catalysts”, Organometallics, 1996, 15, 2672-2674 relates to tridentate zirconium complexes; (5) Baumann, et al., “Synthesis of Titanium and Zirconium Complexes that Contain the Tridentate Diamido Ligand [((t-Bu-d₆)N—O—C₆H₄)₂O]²⁻{[NON}²⁻) and the Living Polymerization of 1-Hexene by Activated [NON]ZrMe2”, Journal of the American Chemical Society, Vol. 119, pp. 3830-3831; (6) Cloke et al., “Zirconium Complexes incorporating the New Tridentate Diamide Ligand [(Me₃Si)N{CH₂CH₂N(SiMe₃)}₂]²⁻(L); the Crystal Structure of [Zr(BH₄)₂L] and [ZrCl{CH(SiMe₃)₂}L]”, J. Chem. Soc. Dalton Trans, pp. 25-30, 1995; (7) Clark et al., “Titanium (IV) complexes incorporating the aminodiamide ligand [(SiMe₃)N{CH₂CH₂N(SiMe₃)}₂]²⁻L); the X-ray crystal structure of [TiMe₂(L)] and [TiCl{CH(SiMe₃)₂}(L)]”, Journal of Organometallic Chemistry, Vol 50, pp. 333-340, 1995; (8) Scollard et al., “Living Polymerization of alpha-olefins by Chelating Diamide Complexes of Titanium”, J. Am. Chem. Soc., Vol 118, No. 41, pp. 10008-10009, 1996; and (9) Guerin et al., “Conformationally Rigid Diamide Complexes: Synthesis and Structure of Titanium (IV) Alkyl Derivatives”, Organometallics, Vol 15, No. 24, pp. 5085-5089, 1996.

Furthermore, U.S. Pat. No. 5,576,460 describes a preparation of arylamine ligands and U.S. Pat. No. 5,889,128 discloses a process for the living polymerization of olefins using initiators having a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. EP 893 454 A1 also describes preferably titanium transition metal amide compounds. In addition, U.S. Pat. No. 5,318,935 discusses amido transition metal compounds and catalyst systems especially for the producing isotactic polypropylene. Polymerization catalysts containing bidentate and tridentate ligands are further discussed in U.S. Pat. No. 5,506,184.

While all these compounds have been described in the art, there is still a need for an improved catalyst system.

SUMMARY OF THE INVENTION

This invention provides for a catalyst system and for its use in polymerizing process.

In one embodiment, the invention is directed to a catalyst system of a Group 15 containing transition metal catalyst compound and a Lewis acid activator and to its use in the polymerization of olefin(s).

In another embodiment, the invention is directed to a catalyst system of a Group 15 containing bidentate or tridentate ligated transition metal catalyst compound and a Lewis acid aluminum containing activator to its use in the polymerization of olefin(s).

In another embodiment, the invention is directed to a catalyst system having a transition metal bound to at least one leaving group and also bound to at least two Group 15 atoms, at least one of which is also bound to a Group 15 or 16 atom through another group, and a Lewis acid aluminum containing activator, and to its use in the polymerization of olefin(s).

In still another embodiment, the invention is directed to a method for supporting the multidentate metal based catalyst system, and to the supported catalyst system itself.

In another embodiment, the invention is directed to a process for polymerizing olefin(s), particularly in a gas phase or slurry phase process, utilizing any one of the catalyst systems or supported catalyst systems discussed above.

DETAILED DESCRIPTION OF THE INVENTION

Introduction

It has been found that catalyst systems of a Group 15 containing transition metal catalyst compound and a Lewis acid aluminum containing activators exhibit commercially acceptable productivity with excellent operability. Also, in particular the catalyst system of the invention is supportable on a support material, preferably for use in a slurry or gas phase polymerization process.

Group 15 Containing Metal Catalyst Compound and Catalyst Systems

In one embodiment, the metal based catalyst compounds of the invention are Group 15 bidentate or tridentate ligated transition metal compound having at least one substituted hydrocarbon group, the preferred Group 15 elements are nitrogen and/or phosphorous, most preferably nitrogen, and the preferred leaving group is a substituted alkyl group having greater than 6 carbon atoms, preferably the alkyl substituted with an aryl group.

The Group 15 containing metal catalyst compounds of the invention generally include a transition metal atom bound to at least one substituted hydrocarbon leaving group and also bound to at least two Group 15 atoms, at least one of which is also bound to a Group 15 or 16 atom through another group.

In one preferred embodiment, at least one of the Group 15 atoms is also bound to a Group 15 or 16 atom through another group, which may be a hydrocarbon group, preferably a hydrocarbon group having 1 to 20 carbon atoms, a heteroatom containing group, preferably silicon, germanium, tin, lead, or phosphorus. In this embodiment, it is further preferred that the Group 15 or 16 atom be bound to nothing or a hydrogen, a Group 14 atom containing group, a halogen, or a heteroatom containing group. Additionally in these embodiment, it is preferred that each of the two Group 15 atoms are also bound to a cyclic group that may optionally be bound to hydrogen, a halogen, a heteroatom or a hydrocarbyl group, or a heteroatom containing group.

In an embodiment of the invention, the Group 15 containing metal compound of the invention is represented by the formulae:

wherein

M is a metal, preferably a transition metal, more preferably a Group 4,5 or 6 metal, even more preferably a Group 4 metal, and most preferably hafnium or zirconium; each X is independently a leaving group, preferably, an anionic leaving group, and more preferably hydrogen, a hydrocarbyl group, a heteroatom, and most preferably an alkyl. In a most preferred embodiment, at least one X is a substituted hydrocarbon group, preferably a substituted alkyl group having more than 6 carbon atoms, more preferably an aryl substituted alkyl group and most preferably a benzyl group.

y is 0 or 1 (when y is 0 group L′ is absent);

n is the oxidation state of M, preferably +2, +3, +4 or +5 and more preferably +4;

m is the formal charge of the YZL or the YZL′ ligand, preferably 0, −1, −2 or −3, and more preferably −2;

L is a Group 15 or 16 element, preferably nitrogen;

L′ is a Group 15 or 16 element or Group 14 containing group, preferably carbon, silicon or germanium;

Y is a Group 15 element, preferably nitrogen or phosphorus, and more preferably nitrogen;

Z is a Group 15 element, preferably nitrogen or phosphorus, and more preferably nitrogen;

R¹ and R² are independently a C₁ to C₂₀ hydrocarbon group, a heteroatom containing group having up to twenty carbon atoms, silicon, germanium, tin, lead, or phosphorus, preferably a C₂ to C₂₀ alkyl, aryl or arylalkyl group, more preferably a linear, branched or cyclic C₂ to C₂₀ alkyl group, most preferably a C₂ to C₆ hydrocarbon group;

R³ is absent or a hydrocarbon group, hydrogen, a halogen, a heteroatom containing group, preferably a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms, more preferably R³ is absent, hydrogen or an alkyl group, and most preferably hydrogen;

R⁴ and R⁵ are independently an alkyl group, an aryl group, substituted aryl group, a cyclic alkyl group, a substituted cyclic alkyl group, a cyclic arylalkyl group, a substituted cyclic arylalkyl group or multiple ring system, preferably having up to 20 carbon atoms, more preferably between 3 and 10 carbon atoms, and even more preferably a C₁ to C₂₀ hydrocarbon group, a C₁ to C₂₀ aryl group or a C₁ to C₂₀ arylalkyl group, or a heteroatom containing group, for example PR₃, where R is an alkyl group;

R¹ and R² may be interconnected to each other, and/or R⁴ and R⁵ may be interconnected to each other;

R⁶ and R⁷ are independently absent, or hydrogen, an alkyl group, halogen, heteroatom or a hydrocarbyl group, preferably a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms, more preferably absent; and

R* is absent, or is hydrogen, a Group 14 atom containing group, a halogen, a heteroatom containing group.

By “formal charge of the YZL or YZL′ ligand”, it is meant the charge of the entire ligand absent the metal and the leaving groups X.

By “R¹ and R² may also be interconnected” it is meant that R¹ and R² may be directly bound to each other or may be bound to each other through other groups. By “R⁴ and R⁵ may also be interconnected” it is meant that R⁴ and R⁵ may be directly bound to each other or may be bound to each other through other groups.

An alkyl group may be a linear, branched alkyl radicals, or alkenyl radicals, alkynyl radicals, cycloalkyl radicals or aryl radicals, acyl radicals, aroyl radicals, alkoxy radicals, aryloxy radicals, alkylthio radicals, dialkylamino radicals, alkoxycarbonyl radicals, aryloxycarbonyl radicals, carbomoyl radicals, alkyl- or dialkyl-carbamoyl radicals, acyloxy radicals, acylamino radicals, aroylamino radicals, straight, branched or cyclic, alkylene radicals, or combination thereof. An arylalkyl group is defined to be a substituted aryl group.

In a preferred embodiment R⁴ and R⁵ are independently a group represented by the following formula:

wherein R⁸ to R¹² are each independently hydrogen, a C₁ to C₄₀ alkyl group, a halide, a heteroatom, a heteroatom containing group containing up to 40 carbon atoms, preferably a C₁ to C₂₀ linear or branched alkyl group, preferably a methyl, ethyl, propyl or butyl group, any two R groups may form a cyclic group and/or a heterocyclic group. The cyclic groups may be aromatic. In a preferred embodiment R⁹, R¹⁰ and R¹² are independently a methyl, ethyl, propyl or butyl group (including all isomers), in a preferred embodiment R⁹, R¹⁰ and R¹² are methyl groups, and R⁸ and R¹¹ are hydrogen.

In a particularly preferred embodiment R⁴ and R⁵ are both a group represented by the following formula:

In this embodiment, M is hafnium or zirconium; each of L, Y, and Z is nitrogen; each of R¹ and R² is a hydrocarbyl group, preferably —CH₂—CH₂—; R³ is hydrogen; and R⁶ and R⁷ are absent.

The Group 15 containing metal catalyst compounds of the invention are prepared by methods known in the art, such as those disclosed in EP 0 893 454 A1, U.S. Pat. No. 5,889,128 and the references cited in U.S. Pat. No. 5,889,128 which are all herein incorporated by reference. U.S. application Ser. No. 09/312,878, filed May 17, 1999, discloses a gas or slurry phase polymerization process using a supported bisamide catalyst, which is also incorporated herein by reference. A preferred direct synthesis of these compounds comprises reacting the neutral ligand, (see for example YZL or YZL′ of Formula I or II) with MX_(n), n is the oxidation state of the metal, each X is an anionic group, such as halide, in a non-coordinating or weakly coordinating solvent, such as ether, toluene, xylene, benzene, methylene chloride, and/or hexane or other solvent having a boiling point above 60° C., at about 20° C. to about 150° C. (preferably 20° C. to 100° C.), preferably for 24 hours or more, then treating the mixture with an excess (such as four or more equivalents) of an alkylating agent, such as methyl magnesium bromide in ether. The magnesium salts are removed by filtration, and the metal complex isolated by standard techniques.

In one embodiment the Group 15 containing metal catalyst compound is prepared by a method comprising reacting a neutral ligand, (see for example YZL or YZL′ of formula 1 or 2) with a compound represented by the formula MX_(n), ( where n is the oxidation state of M, M is a transition metal, and each X is an anionic leaving group) in a non-coordinating or weakly coordinating solvent, at about 20° C. or above, preferably at about 20° C. to about 100° C., then treating the mixture with an excess of an alkylating agent, then recovering the metal complex. In a preferred embodiment the solvent has a boiling point above 60° C., such as toluene, xylene, benzene, and/or hexane. In another embodiment the solvent comprises ether and/or methylene chloride, either being preferable.

Activator and Activation Methods

The above described Group 15 containing metal catalyst compounds are typically activated in various ways to yield catalyst compounds having a vacant coordination site that will coordinate, insert, and polymerize olefin(s). The preferred activator is a Lewis acid compound, more preferably an aluminum based Lewis acid compound, and most preferably a neutral, aluminum based Lewis acid compound having at least one, preferably two, halogenated aryl ligands and one or two additional monoanionic ligands not including halogenated aryl ligands.

The Lewis acid compounds of the invention include those olefin catalyst activator Lewis acids based on aluminum and having at least one bulky, electron-withdrawing ancillary ligand such as the halogenated aryl ligands of tris(perfluorophenyl)borane or tris(perfluoronaphthyl)borane. These bulky ancillary ligands are those sufficient to allow the Lewis acids to function as electronically stabilizing, compatible non-coordinating anions. Stable ionic complexes are achieved when the anions will not be a suitable ligand donor to the strongly Lewis acidic cationic Group 15 containing transition metal cations used in insertion polymerization, i.e., inhibit ligand transfer that would neutralize the cations and render them inactive for polymerization.

The Lewis acids fitting this description can be described by the following formula:

R_(n)Al(ArHal)_(3−n),  (V)

where R is a monoanionic ligand and ArHal is a halogenated C₆ aromatic or higher carbon number polycyclic aromatic hydrocarbon or aromatic ring assembly in which two or more rings (or fused ring systems) are joined directly to one another or together, and n=1 to 2, preferably n=1.

In one embodiment, at least one (ArHal) is a halogenated C₉ aromatic or higher, preferably a fluorinated naphtyl. Suitable non-limiting R ligands include: substituted or unsubstituted C₁ to C₃₀ hydrocarbyl aliphatic or aromatic groups, substituted meaning that at least one hydrogen on a carbon atom is replaced with a hydrocarbyl, halide, halocarbyl, hydrocarbyl or halocarbyl substituted organometalloid, dialkylamido, alkoxy, siloxy, aryloxy, alkysulfido, arylsulfido, alkylphosphido, alkylphosphido or other anionic substituent; fluoride; bulky alkoxides, where bulky refers to C₄ and higher number hydrocarbyl groups, e.g., up to about C₂₀, such as tert-butoxide and 2,6-dimethylphenoxide, and 2,6-di(tert-butyl)phenoxide; —SR; —NR₂, and —PR₂, where each R is independently a substituted or unsubstituted hydrocarbyl as defined above; and, C₁ to C₃₀ hydrocarbyl substituted organometalloid, such as trimethylsilyl.

Examples of ArHal include the phenyl, napthyl and anthracenyl radicals of U.S. Pat. No. 5,198,401 and the biphenyl radicals of WO 97/29845 when halogenated. The use of the terms halogenated or halogenation means for the purposes of this application that at least one third of hydrogen atoms on carbon atoms of the aryl-substituted aromatic ligands are replaced by halogen atoms, and more preferred that the aromatic ligands be perhalogenated. Fluorine is the most preferred halogen.

Other activators or methods of activation are contemplated for use with the aluminum based Lewis acid activators. For example other activators include: alumoxane, modified alumoxane, tri (n-butyl) ammonium tetrakis (pentafluorophenyl) boron, a trisperfluorophenyl boron metalloid precursor or a trisperfluoronaphtyl boron metalloid precursor, polyhalogenated heteroborane anions, trimethylammonium, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tris (2, 2′, 2″-nona-fluorobiphenyl) fluoroaluminate, perchlorates, periodates, iodates and hydrates, (2,2′-bisphenyl-ditrimethylsilicate).4THF and organo-boron-aluminum compound, silylium salts and dioctadecylmethylammonium-bis(tris(pentafluorophenyl)borane)-benzimidazolide.

It is further contemplated by the invention that other catalysts including bulky ligand metallocene-type catalyst compounds and/or conventional-type catalyst compounds can be combined with the Group 15 containing metal catalyst compounds of this invention.

Supports, Carriers and General Supporting Techniques

The above described catalyst systems of a Group 15 containing metal catalyst compound and a Lewis acid aluminum containing activator may be combined with one or more support materials or carriers using one of the support methods well known in the art or as described below. For example, in a most preferred embodiment, a Group 15 containing metal catalyst compound and Lewis acid activator is in a supported form, for example deposited on, contacted with, vaporized with, bonded to, or incorporated within, adsorbed or absorbed in, or on, a support or carrier.

The R group in formula (V) above, or ligand, may also be a covalently bonded to a support material, preferably a metal/metalloid oxide or polymeric support. Lewis base-containing support materials or substrates will react with the Lewis acid activators to form a support bonded Lewis acid compound, a supported activator, where one R group of R_(n)Al(ArHal)_(3−n) is covalently bonded to the support material. For example, where the support material is silica, the Lewis base hydroxyl groups of the silica is where this method of bonding at one of the aluminum coordination sites occurs.

In a preferred embodiment, the support material is a metal or metalloid oxide, preferably having surface hydroxyl groups exhibiting a pK_(a) equal to or less than that observed for amorphous silica, i.e., pK_(a) less than or equal to about 11.

While not wishing to be bound to any particular theory, it is believed that the covalently bound anionic activator, the Lewis acid, is believed to form initially a dative complex with a silanol group, for example of silica (which acts as a Lewis base), thus forming a formally dipolar (zwitterionic) Bronsted acid structure bound to the metal/metalloid of the metal oxide support. Thereafter, the proton of the Bronsted acid appears to protonate an R-group of the Lewis acid, abstracting it, at which time the Lewis acid becomes covalently bonded to the oxygen atom. The replacement R group of the Lewis acid then becomes R′—O—, where R′ is a suitable support material or substrate, for example, silica or hydroxyl group-containing polymeric support. Any support material that contain surface hydroxyl groups are suitable for use in this particular supporting method. Other support material include glass beads. In one embodiment where the support material is a metal oxide composition, these compositions may additionally contain oxides of other metals, such as those of Al, K, Mg, Na, Si, Ti and Zr and should preferably be treated by thermal and/or chemical means to remove water and free oxygen. Typically such treatment is in a vacuum in a heated oven, in a heated fluidized bed or with dehydrating agents such as organo silanes, siloxanes, alkyl aluminum compounds, etc. The level of treatment should be such that as much retained moisture and oxygen as is possible is removed, but that a chemically significant amount of hydroxyl functionality is retained. Thus calcining at up to 800 ° C. or more up to a point prior to decomposition of the support material, for several hours is permissible, and if higher loading of supported anionic activator is desired, lower calcining temperatures for lesser times will be suitable. Where the metal oxide is silica, loadings to achieve from less than 0.1 mmol to 3.0 mmol activator/g SiO₂ are typically suitable and can be achieved, for example, by varying the temperature of calcining from 200 to 800+° C. See Zhuralev, et al, Langmuir 1987, Vol. 3, 316 where correlation between calcining temperature and times and hydroxyl contents of silica's of varying surface areas is described. The tailoring of hydroxyl groups available as attachment sites can also be accomplished by the pre-treatment, prior to addition of the Lewis acid, with a less than stoichiometric amount of the chemical dehydrating agents. Preferably those used will be used sparingly and will be those having a single ligand reactive with the silanol groups (e.g., (CH₃)₃SiCl), or otherwise hydrolyzable, so as to minimize interference with the reaction of the transition metal catalyst compounds with the bound activator. If calcining temperatures below 400° C. are employed, difunctional coupling agents (e.g., (CH₃)₂SiCl₂) may be employed to cap hydrogen bonded pairs of silanol groups which are present under the less severe calcining conditions. See for example, “Investigation of Quantitative SiOH Determination by the Silane Treatment of Disperse Silica”, Gorski, et al, Journ. of Colloid and Interface Science, Vol. 126, No. 2, December 1988, for discussion of the effect of silane coupling agents for silica polymeric fillers that will also be effective for modification of silanol groups on the catalyst supports of this invention. Similarly, use of the Lewis acid in excess of the stoichiometric amount needed for reaction with the transition metal compounds will serve to neutralize excess silanol groups without significant detrimental effect for catalyst preparation or subsequent polymerization.

Polymeric supports are preferably hydroxyl-functional-group-containing polymeric substrates, but functional groups may be any of the primary alkyl amines, secondary alkyl amines, and others, where the groups are structurally incorporated in a polymeric chain and capable of a acid-base reaction with the Lewis acid such that a ligand filling one coordination site of the aluminum is protonated and replaced by the polymer incorporated functionality. See, for example, the functional group containing polymers of U.S. Pat. No. 5,288,677, which is herein incorporated by reference.

Other supports include silica, alumina, silica-alumina, magnesia, titania, zirconia, magnesium chloride, montmorillonite, phyllosilicate, zeolites, talc, clays, silica-chromium, silica-alumina, silica-titania, porous acrylic polymers.

In one embodiment, the support material or carrier, most preferably an inorganic oxide has a surface area in the range of from about 10 to about 100 m²/g, pore volume in the range of from about 0.1 to about 4.0 cc/g and average particle size in the range of from about 5 to about 500 μm. More preferably, the surface area of the carrier is in the range of from about 50 to about 500 m²/g, pore volume of from about 0.5 to about 3.5 cc/g and average particle size of from about 10 to about 200 μm. Most preferably the surface area of the carrier is in the range is from about 100 to about 400 m²/g, pore volume from about 0.8 to about 5.0 cc/g and average particle size is from about 5 to about 100 μm. The average pore size of the carrier of the invention typically has pore size in the range of from 10 to 1000 Å, preferably 50 to about 500 Å, and most preferably 75 to about 450 Å.

There are various other methods in the art for supporting a polymerization catalyst compound or catalyst system of the invention.

In a preferred embodiment, the invention provides for a Group 15 containing metal catalyst system includes a surface modifier that is used in the preparation of the supported catalyst system as described in PCT publication WO 96/11960, which is herein fully incorporated by reference. The catalyst systems of the invention can be prepared in the presence of an olefin, for example hexene-1.

In a preferred embodiment, the Group 15 containing metal catalyst system can be combined with a carboxylic acid salt of a metal ester, for example aluminum carboxylates such as aluminum mono, di- and tri-stearates, aluminum octoates, oleates and cyclohexylbutyrates, as described in U.S. application Ser. No. 09/113,216, filed Jul. 10, 1998 pending.

A preferred method for producing a supported Group 15 containing metal catalyst system is described below and is described in U.S. application Ser. Nos. 265,533, filed Jun. 24, 1994 abandoned and 265,532, filed Jun. 24, 1994 abandoned and PCT publications WO 96/00245 and WO 96/00243 both published Jan. 4, 1996, all of which are herein fully incorporated by reference. In this preferred method, the Group 15 containing metal catalyst compound is slurried in a liquid to form a solution and a separate solution is formed containing a Lewis acid activator and a liquid. The liquid may be any compatible solvent or other liquid capable of forming a solution or the like with the Group 15 containing metal catalyst compounds and/or Lewis acid activator. In the most preferred embodiment the liquid is a cyclic aliphatic or aromatic hydrocarbon, most preferably toluene. The Group 15 containing metal catalyst compounds and Lewis acid activator solutions are mixed together and added to a porous support such that the total volume of Group 15 containing metal catalyst compound solution and the Lewis acid activator solution or the Group 15 containing metal catalyst compound solution and Lewis acid activator solution is less than four times the pore volume of the porous support, more preferably less than three times, even more preferably less than two times; preferred ranges being from 1.1 times to 3.5 times range and most preferably in the 1.2 to 3 times range.

Procedures for measuring the total pore volume of a porous support are well known in the art. Details of one of these procedures is discussed in Volume 1, Experimental Methods in Catalytic Research (Academic Press, 1968) (specifically see pages 67-96). This preferred procedure involves the use of a classical BET apparatus for nitrogen absorption. Another method well known in the art is described in Innes, Total Porosity and Particle Density of Fluid Catalysts By Liquid Titration, Vol. 28, No. 3, Analytical Chemistry 332-334 (March, 1956).

The mole ratio of the metal of the activator component to the metal component of the Group 15 containing metal catalyst compound is preferably in the range of between 0.3:1 to 3:1.

In one embodiment of the invention, olefin(s), preferably C₂ to C₃₀ olefin(s) or alpha-olefin(s), preferably ethylene or propylene or combinations thereof are prepolymerized in the presence of the catalyst system of the invention prior to the main polymerization. The prepolymerization can be carried out batchwise or continuously in gas, solution or slurry phase including at elevated pressures. The prepolymerization can take place with any olefin monomer or combination and/or in the presence of any molecular weight controlling agent such as hydrogen. For examples of prepolymerization procedures, see U.S. Pat. Nos. 4,748,221, 4,789,359, 4,923,833, 4,921,825, 5,283,278 and 5,705,578 and European publication EP-B-0279 863 and PCT Publication WO 97/44371 all of which are herein fully incorporated by reference.

Polymerization Process

The catalyst systems, supported catalyst systems or compositions of the invention described above are suitable for use in any prepolymerization and/or polymerization process over a wide range of temperatures and pressures. The temperatures may be in the range of from −60° C. to about 280° C., preferably from 50° C. to about 200° C., and the pressures employed may be in the range from 1 atmosphere to about 500 atmospheres or higher.

Polymerization processes include solution, gas phase, slurry phase and a high pressure process or a combination thereof. Particularly preferred is a gas phase or slurry phase polymerization of one or more olefins at least one of which is ethylene or propylene.

In one embodiment, the process of this invention is directed toward a solution, high pressure, slurry or gas phase polymerization process of one or more olefin monomers having from 2 to 30 carbon atoms, preferably 2 to 12 carbon atoms, and more preferably 2 to 8 carbon atoms. The invention is particularly well suited to the polymerization of two or more olefin monomers of ethylene, propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, octene-1 and decene-1.

Other monomers useful in the process of the invention include ethylenically unsaturated monomers, diolefins having 4 to 18 carbon atoms, conjugated or nonconjugated dienes, polyenes, vinyl monomers and cyclic olefins. Non-limiting monomers useful in the invention may include norbornene, norbornadiene, isobutylene, isoprene, vinylbenzocyclobutane, styrenes, alkyl substituted styrene, ethylidene norbornene, dicyclopentadiene and cyclopentene.

In the most preferred embodiment of the process of the invention, a copolymer of ethylene is produced, where with ethylene, a comonomer having at least one alpha-olefin having from 4 to 15 carbon atoms, preferably from 4 to 12 carbon atoms, and most preferably from 4 to 8 carbon atoms, is polymerized in a gas phase process.

In another embodiment of the process of the invention, ethylene or propylene is polymerized with at least two different comonomers, optionally one of which may be a diene, to form a terpolymer.

In one embodiment, the invention is directed to a polymerization process, particularly a gas phase or slurry phase process, for polymerizing propylene alone or with one or more other monomers including ethylene, and/or other olefins having from 4 to 12 carbon atoms.

Typically in a gas phase polymerization process a continuous cycle is employed where in one part of the cycle of a reactor system, a cycling gas stream, otherwise known as a recycle stream or fluidizing medium, is heated in the reactor by the heat of polymerization. This heat is removed from the recycle composition in another part of the cycle by a cooling system external to the reactor. Generally, in a gas fluidized bed process for producing polymers, a gaseous stream containing one or more monomers is continuously cycled through a fluidized bed in the presence of a catalyst under reactive conditions. The gaseous stream is withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product is withdrawn from the reactor and fresh monomer is added to replace the polymerized monomer. (See for example U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670, 5,317,036, 5,352,749, 5,405,922, 5,436,304, 5,453,471, 5,462,999, 5,616,661 and 5,668,228, all of which are fully incorporated herein by reference.)

The reactor pressure in a gas phase process may vary from about 100 psig (690 kPa) to about 500 psig (3448 kPa), preferably in the range of from about 200 psig (1379 kPa) to about 400 psig (2759 kPa), more preferably in the range of from about 250 psig (1724 kPa) to about 350 psig (2414 kPa).

The reactor temperature in a gas phase process may vary from about 30° C. to about 120° C., preferably from about 60° C. to about 115° C., more preferably in the range of from about 70° C. to 110° C., and most preferably in the range of from about 70° C. to about 95° C.

Other gas phase processes contemplated by the process of the invention include series or multistage polymerization processes. Also gas phase processes contemplated by the invention include those described in U.S. Pat. Nos. 5,627,242, 5,665,818 and 5,677,375, and European publications EP-A-0 794 200 EP-B1-0 649 992, EP-A-0 802 202 and EP-B-634 421 all of which are herein fully incorporated by reference.

In a preferred embodiment, the reactor utilized in the present invention is capable and the process of the invention is producing greater than 500 lbs of polymer per hour (227 Kg/hr) to about 200,000 lbs/hr (90,900 Kg/hr) or higher of polymer, preferably greater than 1000 lbs/hr (455 Kg/hr), more preferably greater than 10,000 lbs/hr (4540 Kg/hr), even more preferably greater than 25,000 lbs/hr (11,300 Kg/hr), still more preferably greater than 35,000 lbs/hr (15,900 Kg/hr), still even more preferably greater than 50,000 lbs/hr (22,700 Kg/hr) and most preferably greater than 65,000 lbs/hr (29,000 Kg/hr) to greater than 100,000 lbs/hr (45,500 Kg/hr).

A slurry polymerization process generally uses pressures in the range of from about 1 to about 50 atmospheres and even greater and temperatures in the range of 0° C. to about 120° C. In a slurry polymerization, a suspension of solid, particulate polymer is formed in a liquid polymerization diluent medium to which ethylene and comonomers and often hydrogen along with catalyst are added. The suspension including diluent is intermittently or continuously removed from the reactor where the volatile components are separated from the polymer and recycled, optionally after a distillation, to the reactor. The liquid diluent employed in the polymerization medium is typically an alkane having from 3 to 7 carbon atoms, preferably a branched alkane. The medium employed should be liquid under the conditions of polymerization and relatively inert. When a propane medium is used the process must be operated above the reaction diluent critical temperature and pressure. Preferably, a hexane or an isobutane medium is employed.

A preferred polymerization technique of the invention is referred to as a particle form polymerization, or a slurry process where the temperature is kept below the temperature at which the polymer goes into solution. Such technique is well known in the art, and described in for instance U.S. Pat. No. 3,248,179 which is fully incorporated herein by reference. Other slurry processes include those employing a loop reactor and those utilizing a plurality of stirred reactors in series, parallel, or combinations thereof Non-limiting examples of slurry processes include continuous loop or stirred tank processes. Also, other examples of slurry processes are described in U.S. Pat. No. 4,613,484, which is herein fully incorporated by reference.

In an embodiment the reactor used in the slurry process of the invention is capable of and the process of the invention is producing greater than 2000 lbs of polymer per hour (907 Kg/hr), more preferably greater than 5000 lbs/hr (2268 Kg/hr), and most preferably greater than 10,000 lbs/hr (4540 Kg/hr). In another embodiment the slurry reactor used in the process of the invention is producing greater than 15,000 lbs of polymer per hour (6804 Kg/hr), preferably greater than 25,000 lbs/hr (11,340 Kg/hr) to about 100,000 lbs/hr (45,500 Kg/hr).

Examples of solution processes are described in U.S. Pat. Nos. 4,271,060, 5,001,205, 5,236,998 and 5,589,555 and PCT WO 99/32525, which are fully incorporated herein by reference

A process of the invention is where the process, preferably a slurry or gas phase process is operated in the presence of the catalyst system of the invention and in the absence of or essentially free of any scavengers, such as triethylaluminum, trimethylaluminum, tri-isobutylaluminum and tri-n-hexylaluminum and diethyl aluminum chloride, dibutyl zinc and the like. This process is described in PCT publication WO 96/08520 and U.S. Pat. No. 5,712,352 and 5,763,543, which are herein fully incorporated by reference.

In an embodiment, the method of the invention provides for injecting an unsupported metal catalyst system of the invention into a reactor, particularly a gas phase reactor. In one embodiment the catalyst system is used in the unsupported form, preferably in a liquid form such as described in U.S. Pat. Nos. 5,317,036 and 5,693,727 and European publication EP-A-0 593 083, all of which are herein incorporated by reference. The polymerization catalyst in liquid form can be fed with an activator together or separately to a reactor using the injection methods described in PCT publication WO 97/46599, which is fully incorporated herein by reference. Where an unsupported catalyst system is used the mole ratio of the metal of the Lewis acid activator component to the metal of the Group 15 containing metal catalyst compound is in the range of between 0.3:1 to 10,000:1, preferably 100:1 to 5000:1, and most preferably 500:1 to 2000:1.

Polymer Products

The polymers produced by the process of the invention can be used in a wide variety of products and end-use applications. The polymers produced by the process of the invention include linear low density polyethylene, elastomers, plastomers, high density polyethylenes, medium density polyethylenes, low density polyethylenes, polypropylene and polypropylene copolymers.

The polymers, typically ethylene based polymers, have a density in the range of from 0.86 g/cc to 0.97 g/cc, preferably in the range of from 0.88 g/cc to 0.965 g/cc, more preferably in the range of from 0.900 g/cc to 0.96 g/cc, even more preferably in the range of from 0.905 g/cc to 0.95 g/cc, yet even more preferably in the range from 0.910 g/cc to 0.940 g/cc, and most preferably greater than 0.915 g/cc, preferably greater than 0.920 g/cc, and most preferably greater than 0.925 g/cc. Density is measured in accordance with ASTM-D-1238.

The polymers produced by the process of the invention typically have a molecular weight distribution, a weight average molecular weight to number average molecular weight (M_(w)/M_(n)) of greater than 1.5 to about 15, particularly greater than 2 to about 10, more preferably greater than about 2.2 to less than about 8, and most preferably from 2.5 to 8.

Also, the polymers of the invention typically have a narrow composition distribution as measured by Composition Distribution Breadth Index (CDBI). Further details of determining the CDBI of a copolymer are known to those skilled in the art. See, for example, PCT Patent Application WO 93/03093, published Feb. 18, 1993, which is fully incorporated herein by reference.

The polymers of the invention in one embodiment have CDBI's generally in the range of greater than 50% to 100%, preferably 99%, preferably in the range of 55% to 85%, and more preferably 60% to 80%, even more preferably greater than 60%, still even more preferably greater than 65%.

In another embodiment, polymers produced using a catalyst system of the invention have a CDBI less than 50%, more preferably less than 40%, and most preferably less than 30%.

The polymers of the present invention in one embodiment have a melt index (MI) or (I₂) as measured by ASTM-D-1238-E in the range from no measurable flow to 1000 dg/min, more preferably from about 0.01 dg/min to about 100 dg/min, even more preferably from about 0.1 dg/min to about 50 dg/min, and most preferably from about 0.1 dg/min to about 10 dg/min.

The polymers of the invention in an embodiment have a melt index ratio (I₂₁/I₂) (I₂₁ is measured by ASTM-D-1238-F) of from 10 to less than 25, more preferably from about 15 to less than 25.

The polymers of the invention in a preferred embodiment have a melt index ratio (I₂₁/I₂) (I₂₁ is measured by ASTM-D-1238-F) of from preferably greater than 25, more preferably greater than 30, even more preferably greater that 40, still even more preferably greater than 50 and most preferably greater than 65. In an embodiment, the polymer of the invention may have a narrow molecular weight distribution and a broad composition distribution or vice-versa, and may be those polymers described in U.S. Pat. No. 5,798,427 incorporated herein by reference.

In yet another embodiment, propylene based polymers are produced in the process of the invention. These polymers include atactic polypropylene, isotactic polypropylene, hemi-isotactic and syndiotactic polypropylene. Other propylene polymers include propylene block or impact copolymers. Propylene polymers of these types are well known in the art see for example U.S. Pat. Nos. 4,794,096, 3,248,455, 4,376,851, 5,036,034 and 5,459,117, all of which are herein incorporated by reference.

The Group 15 containing metal compound, when used alone, produces a high weight average molecular weight M_(w) polymer (such as for example above 100,000, preferably above 150,000, preferably above 200,000, preferably above 250,000, more preferably above 300,000).

The polymers of the invention may be blended and/or coextruded with any other polymer. Non-limiting examples of other polymers include linear low density polyethylenes, elastomers, plastomers, high pressure low density polyethylene, high density polyethylenes, polypropylenes and the like.

Polymers produced by the process of the invention and blends thereof are useful in such forming operations as film, sheet, and fiber extrusion and co-extrusion as well as blow molding, injection molding and rotary molding. Films include blown or cast films formed by coextrusion or by lamination useful as shrink film, cling film, stretch film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, membranes, etc. in food-contact and non-food contact applications. Fibers include melt spinning, solution spinning and melt blown fiber operations for use in woven or non-woven form to make filters, diaper fabrics, medical garments, geotextiles, etc. Extruded articles include medical tubing, wire and cable coatings, pipe, geomembranes, and pond liners. Molded articles include single and multi-layered constructions in the form of bottles, tanks, large hollow articles, rigid food containers and toys, etc.

EXAMPLES

In order to provide a better understanding of the present invention including representative advantages thereof, the following examples are offered.

Synthesis of Al (C₆F₅)₃.toluene was prepared in accordance with method of described in EP 0 694 548 A1, which is fully incorporated by reference.

Example 1 Preparation of [(2,4,6-Me₃C₆H₂)NHCH₂CH₂]₂NH Ligand (HN3)

A 2 L one-armed Schlenk flask was charged with a magnetic stir bar, diethylenetriamine (23.450 g, 0.227 mol), 2-bromomesitylene (90.51 g, 0.455 mol), tris(dibenzylideneacetone)dipalladium (1.041 g, 1.14 mmol), racemic-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (racemic BINAP) (2.123 g, 3.41 mmol), sodium tert-butoxide (65.535 g, 0.682 mol), and toluene (800 mL) under dry, oxygen-free nitrogen. The reaction mixture was stirred and heated to 100 C. After 18 h the reaction was complete, as judged by proton NMR spectroscopy. All remaining manipulations can be performed in air. All solvent was removed under vacuum and the residues dissolved in diethyl ether (1 L). The ether was washed with water (three times with 250 mL) followed by saturated aqueous NaCl (180 g in 500 mL) and dried over magnesium sulfate (30 g). Removal of the ether in vacuo yielded a red oil which was dried at 70 C. for 12 h under vacuum (yield: 71.10 g, 92%). ¹H NMR (C₆D₆) δ6.83 (s, 4), 3.39 (br s, 2), 2.86 (t, 4), 2.49 (t, 4), 2.27 (s, 12), 2.21 (s, 6), 0.68 (br s, 1).

Example 2 Preparation of {[(2,4,6-Me₃C₆H₂)NCH₂CH₂]₂NH}Zr(CH₂Ph)₂(Zr—NH3)

A 500 mL round bottom flask was charged with a magnetic stir bar, tetrabenzyl zirconium (Boulder Scientific, Mead, Colo.) (41.729 g, 91.56 mmol), and 300 mL of toluene under dry, oxygen-free nitrogen. Solid HN3 ligand above (32.773 g, 96.52 mmol) was added with stirring over 1 minute (the desired compound precipitates). The volume of the slurry was reduced to 100 mL and 300 mL of pentane added with stirring. The solid yellow-orange product was collected by filtration and dried under vacuum (44.811 g, 80% yield). ¹H NMR(C₆D₆) δ7.22-6.81 (m, 12), 5.90 (d, 2), 3.38 (m, 2), 3.11 (m, 2), 3.01 (m, 1), 2.49 (m, 4), 2.43 (s, 6), 2.41 (s, 6), 2.18 (s, 6), 1.89 (s, 2), 0.96 (s, 2).

Example 3 Preparation of {[(2,4,6-Me₃C₆H₂)NCH₂CH₂]₂NH}Hf(CH₂Ph)₂(Hf—HN₃)

A 250 mL round bottom flask was charged with a magnetic stir bar, tetrabenzyl hafnium (4.063 g, 7.482 mmol), and 150 mL of toluene under dry, oxygen-free nitrogen. Solid triamine ligand above (2.545 g, 7.495 mmol) was added with stirring over 1 minute (the desired compound precipitates). The volume of the slurry was reduced to 30 mL and 120 mL of pentane added with stirring. The solid pale yellow product was collected by filtration and dried under vacuum (4.562 g, 87% yield). ¹H NMR(C₆D₆) δ7.21-6.79 (m, 12), 6.16 (d, 2), 3.39 (m, 2), 3.14 (m, 2), 2.65 (s, 6), 2.40 (s, 6), 2.35 (m, 2), 2.23 (m, 2), 2.19 (s, 6) 1.60 (s, 2), 1.26 (s, 2), NH obscured.

Example 4 Preparation of Silica Bound Aluminum (Si—O—Al(C₆F₅)₂)

A sample of 40.686 g of silica (Davison 948, calcined at 600 C, available from W. R. Grace, Davison Division, Baltimore, Md.) was slurried in 300 mL of toluene in a 500 mL round bottom flask. Solid Al(C₆F₅)₃.toluene (15.470 g, 24.90 mmol) was added and the mixture stirred for 30 minutes. The mixture was allowed to stand for 18 hours. The silica bound aluminum was isolated by filtration and dried for 6 hours under vacuum with a yield of 49.211 g.

Example 5

Preparation of Catalyst A

To 1.000 g of silica bound aluminum (from Example 4 above) in 20 mL of toluene was added Zr—HN3 (0.076 g, 0.124 mmol) in 5 mL of toluene. The mixture was stirred for 30 minutes. The silica turned orange-red from colorless. The silica was isolated by filtration and dried under vacuum for 6 hours with a yield of 1.051 g. The final transition metal loading was 116 μmol/g, transition metal to silica bound aluminum.

Example 6

Preparation of Catalyst B

To 1.000 g of silica bound aluminum (from Example 4 above) in 20 mL of toluene was added Hf—HN3 (0.087 g, 0.125 mmol) in 5 mL of toluene. The mixture was stirred for 30 minutes. The silica turned orange-red from colorless. The silica was isolated by filtration and dried under vacuum for 6 hours with a yield of 1.059 g. The final transition metal loading was 115 μmol/g, transition metal to silica bound aluminum.

Example 7

Slurry-Phase Ethylene-Hexene Polymerization with Catalyst A

Polymerization was performed in the slurry-phase in a 1-liter autoclave reactor equipped with a mechanical stirrer, an external water jacket for temperature control, a septum inlet and vent line, and a regulated supply of dry nitrogen and ethylene. The reactor was dried and degassed at 160° C. Isobutane (400 mL) is added as a diluent, 35 mL of 1-hexene, and 0.7 mL of a 25 weight percent trioctyl aluminum in hexane is added as a scavenger using a gas tight syringe. The reactor was heated to 60° C. 0.100 g of finished Catalyst A was added with ethylene pressure and the reactor was pressurized with 78 psi (538 kPa) of ethylene. The polymerization was continued for 30 minutes while maintaining the reactor at 60° C. and 78 psi (538 kPa) by constant ethylene flow. The reaction was stopped by rapid cooling and vented. 70.0 g of copolymer was obtained (Flow Index (FI)=no flow, activity=2320 g polyethylene/mmol catalyst.atm.h, 10.5 weight percent 1-hexene incorporation).

Example 8

Slurry-Phase Ethylene Polymerization with Catalyst B

Polymerization was performed in the slurry-phase in a 1-liter autoclave reactor equipped with a mechanical stirrer, an external water jacket for temperature control, a septum inlet and vent line, and a regulated supply of dry nitrogen and ethylene. The reactor was dried and degassed at 160° C. Isobutane (400 mL) was added as a diluent and 0.7 mL of a 25 weight percent trioctyl aluminum solution in hexane was added as a scavenger using a gas tight syringe. The reactor was heated to 90° C. 0.200 g of finished Catalyst B was added with ethylene pressure and the reactor was pressurized with 134 psi (924 kPa) of ethylene. The polymerization was continued for 30 minutes while maintaining the reactor at 90° C. and 134 psi (924 kPa) by constant ethylene flow. The reaction was stopped by rapid cooling and vented. 37.4 g of polyethylene was obtained (FI=no flow, activity=364 g polyethylene/mmol catalys.atm.h).

Example 9

Slurry-Phase Ethylene-Hexene Polymerization with Catalyst B

Polymerization was performed in the slurry-phase in a 1-liter autoclave reactor equipped with a mechanical stirrer, an external water jacket for temperature control, a septum inlet and vent line, and a regulated supply of dry nitrogen and ethylene. The reactor was dried and degassed at 160° C. Isobutane (400 mL) is added as a diluent, 35 mL of 1-hexene, and 0.7 mL of a 25 weight percent trioctyl aluminum in hexane is added as a scavenger using a gas tight syringe. The reactor was heated to 90° C. 0.100 g of finished catalyst B was added with ethylene pressure and the reactor was pressurized with 113 psi (889 kPa) of ethylene. The polymerization was continued for 25 minutes while maintaining the reactor at 90° C. and 113 psi (889 kPa) by constant ethylene flow. The reaction was stopped by rapid cooling and vented. 68.0 g of polyethylene was obtained (FI=no flow, activity=1650 g polyethylene/mmol catalyst.atm.h).

While the present invention has been described and illustrated by reference to particular embodiments, those of ordinary skill in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. For example, it is contemplated that two or more supported Group 15 containing catalyst compositions of the invention can be used in a single or in multiple polymerization reactor configurations. For this reason, then, reference should be made solely to the appended claims for purposes of determining the true scope of the present invention. 

We claim:
 1. A process for polymerizing olefin(s) in the presence of a catalyst system comprising a Group 15 containing bidentate or tridentate ligated metal catalyst compound and a Lewis acid aluminum containing activator, wherein the Group 15 containing metal compound is represented by the formulae:

wherein M is metal; each X is a leaving group; y is 0 or 1; n is the oxidation state of M; m is the formal charge of Y, Z and L or of Y, Z and L′; L is a Group 15 or 16 element; L′ is a Group 15 or 16 element or Group 14 containing group; Y is a Group 15 element; Z is a Group 15 element; R¹ and R² are independently a C₁ to C₂₀ hydrocarbon group, a heteroatom containing group having up to twenty carbon atoms, silicon, germanium, tin, lead, or phosphorus; R³ is absent, a hydrocarbon group, hydrogen, a halogen, or a heteroatom containing group; R⁴ and R⁵ are independently an alkyl group, an aryl group, a substituted aryl group, a cyclic alkyl group, a substituted cyclic alkyl group, a cyclic arylalkyl group, a substituted cyclic arylalkyl group or a multiple ring system; R¹ and R² may be interconnected to each other, and/or R⁴ and R⁵ may be interconnected to each other; R⁶ and R⁷ are independently absent, hydrogen, an alkyl group, halogen, heteroatom or a hydrocarbyl group; and R* is absent, hydrogen, a Group 14 atom containing group, a halogen, or a heteroatom containing group; and wherein the Lewis acid aluminum containing activator is represented by the formula: R_(n)Al(ArHal)_(3−n), wherein R is a monoanionic ligand; ArHal is a halogenated C₆ aromatic or higher carbon number polycyclic aromatic hydrocarbon or aromatic ring assembly in which two or more rings or fused ring systems are joined directly to one another or together; and n=1 to
 2. 2. The process of claim 1 wherein R⁴ and R⁵ are represented by the formula:

wherein R⁸ to R¹² are each independently hydrogen, a C₁ to C₄₀ alkyl group, a halide, a heteroatom, or a heteroatom containing group containing up to 40 carbon atoms, wherein any two R groups may form a cyclic group and/or a heterocyclic group, and wherein the cyclic groups may be aromatic.
 3. The process of claim 2 wherein R⁹, R¹⁰ and R¹² are independently a methyl, ethyl, propyl or butyl group and X is a substituted alkyl group having greater than 6 carbon atoms.
 4. The process of claim 2 wherein R⁹, R¹⁰ and R¹² are methyl groups, and R⁸ and R¹¹ are hydrogen and X is a alkyl substituted with an aryl group.
 5. The process of claim 1 wherein L, Y, and Z are nitrogen, R¹ and R² are a hydrocarbon radical, R³ is hydrogen, and R⁶ and R⁷ are absent.
 6. The process of claim 1 wherein L and Z are nitrogen, L′ is a hydrocarbyl radical, and R⁶and R⁷ are absent.
 7. The process of claim 1 wherein the catalyst system is supported on a carrier.
 8. The process of claim 1 wherein the process is a continuous gas phase process.
 9. The process of claim 1 wherein the process is a continuous slurry phase process.
 10. The process of claim wherein the olefin(s) is ethylene or propylene.
 11. The process of claim 1 wherein the olefin(s) are ethylene and at least one other monomer having from 3 to 20 carbon atoms.
 12. The process of claim 1 wherein the catalyst system further comprises an activator. 